Electric lamp



July 28, 1925.

T. J. MURPHY ELECTRIC LAMP Filed June '7, 1920 ing had to the accompanying Patented July 28, 19 25.

THOMAS J. MURPHY, OF NEW YORK,

N. 21, ABSIGNOR OF ONE-HALF '10 JAMES P. B.

DUFFY, OF ROCHESTER, NEW YORK.

ELECTRIC LAMP.

Application and June 7,

To all whom it may concern. I

Be it known that I, THOMAS J. MURPHY, a sub'ect to the King of Great Britain, and

1920. Serial No. amass.

prevent the tungsten sleeves 2 from slipping off the wires 3. p The sleeves 2 are loosey mounted on the wires 3 so that they can a resident of New York in the country; of\be easily rotated around the wires 3. This New York and State of New York, ve made an Invention Appertaining to Electric Lamps; and I do hereby declare the following to be a full, clear, and exact descri tion of the invention, such as will enab 0 others skilled in the art to which it appertains to make and use the same reference bedrawin and to the characters of reference marke thereon. which form a part of this specification. M invention has for its object to. rovide a tri-electrode enclosed arc lamp. t particularly has for its object to provide a lamp having tungsten electrodes which are mounted in juxtapositionto produce efiicient arcs between two of the electrodes and one of the electrodes. It also has for its object to prevent dissipation of the heat through the means supporting the electrodes and'c6nsequently to greatly increase the lighting efiiciency of the lamp. The invention has for its object other advantages and features that will appear from the following description and from the drawings.

The invention may be contained in electrode lamps of different forms. To illustrate a practical application of the invention I have shown a tri-electrode tungsten lam The tungsten lamp selected is illustrated in the accompanying drawing.

Figure 1 of the drawing illustrates a side view of the lamp. Fig. 2 illustrates a larger view to show the manner in .which the electrodes are supported. Fig. 3 illustrates diagrammatically a system to which the lamp 18 connected.

1 is the glass bulb of the lamp of the form well known in the art. The glass bu b may be mounted or secured in a suitable sleeve for connecting it in'a lighting circuit. The bulb is preferably filled with an inert gas such as argon or nitrogen.

The tun ten electrodes 2 are supported within the ulb 1 in proximity to each other.

They are formed preferably in the formof' small cylinders or sleeves and are located on tungsten wires 3 which are supported in nickel tubular members 4. The wires 3 may be formed with a shoulder 5 and when the sleeves 2 are placed over the wires 3, the ends of the wires 8 may be headed as at 8 to tubular members' l. Each tubular member 4 being made in the form of a tube has a small cross sectional area of metal compared to its strength and consequentl conduction of heat is decreased. The'tu ular members 4 are connected with suitable wires 6, having a coefficient of expansion substantially the same as that of the lass, in the manner well known in the art. e wires 6 are connected to the wires 7 that make connection with the parts of the sleeve of the lamp.

The electrodes 2 are located in a row and their axes extend preferably parallel to the axis of the bulbyof the lamp. The middle electrode is connected to one side of the source of current supply while the end electrodes are connected to the other side of the source of current supply. In starting, the middle electrode is connected with the negative side of the circuit where the lam is connected to a source of direct current and the end electrodes are connected to the positive side of the source of direct current sup- It has been found that arcs may then rent. Once the arcs are established the current may be reversed and so as to connect thecenter electrode with the positive side of the source of direct current supply and the end electrodes with the negative side and thereby increase the source of light in the center electrode. This will concentrate the major portion of the light in one electrode, namely, the center electrode, which will be exceedingly advantageous when the lamp is used in picture pro ecting apparatus since the light will originate substantially at the single point and thus produce better focusing results on the screens.

In Figure 3 is shown diagrammatically a system' 'fo'r operating the lamp. The main supply wires 10 and 11 connect through a reversing switch and through the resistance coils 13 with the electrodes of the lamp. The arcs between the electrodes, however, are established by producing high voltage of alternately or mterrupted currents in t is circuit of the. electrodes, in order to break down the resistance between the electrodes. This is done in the manner well known in the art by roducingha spark between the electrode w ich will eat the electrodes locally and at the same time aflord a means for the passa e of the lo w voltage current supplied -b tie main lines 10 and 11. A Ruhmkor coil is connected to the lines 10 and 11 through its vibrator 13'. This being in a shunt circuit is provided with a resistance coil 14: The secondary 15 of the Ruhmkorff coil is connected to the outside electrodes. A ga is located in the circuit 16 of the coil 15 hetween theelectrodes 17. A condenser 18 is connected across the ends ofthe coil 15 to produce in. conjunction with the circuit breaker or vibrator 14, a higher vibratory rate or high frequency of oscillation in the current in the manner well known in the art that will produce high tension s arks across the electrodes of the lam e high tension current produced at t e break of the rimary 19 is multiplied in its intensity by t e coil 15 and it breaks across the gap between the electrodes 17 and. between the electrodes 2 of the lamp and inasmuch as the electrodes of the lamp are connected to the main lines 10 and 11 through the reversin switch 12, the arcs from the current supp ied through'the lines 10 and 11 will immediately be established on the arcs or sparks produced by the hi h tension current. The coils 13 are mere y resistance coils and although they are located across the gap between the two outside electrodes 2, yet because of the nature of the oscillatory current roduced by the transformer coil 15, the con enser 18 located across the terminals of the coil 15 and the spark gap 17, there will be a potential across t 1 e are up, 111 accordance with well known facts, w nch Wlll break it down and permit.

the lamp to start.

The arcs will thus be divided as between trodes. It has been found that the arcs will beestablished easier by connecting the center electrode with the negative side of the one terminal which has many advantages particularly in connection with moving pictures and microscopic projection.

I claim 1. In an electric lamp, three tungsten sleeves, three sulpporting wires loosely connected to the s caves, and means for supporting the wires in the lamps.

2. In a tri-electrode lamp, three tungsten sleeves located in parallel relation to each other, tungsten w res for supporting the sleeves, the sleeves loosely connected to the wires and -so as to permlt' free rotation of the sleeves with res ect to the wires.

8. The process 0 operating an arc lamp havin more than two electrodes at least two 0 the electrodes located farther a art than they are to a third electrode, w ich consists in connecting at least two of the electrodes with one terminal of a source of direct current supply, and the said one electrode with the other terminal of the source of supply, and making the lastnamed electrode the negative electrode, and formin high tension sparks between the last name electrode and the said at least two of the electrodes, and reversing the current so as to make the said last named one electrode the positive electrode.

.In testimony whereof I have hereunto signed my name to this specification.

THOMAS J. MURPHY.

the center electrode and the two outer elec- 

